and the [installation and server configuration documentation](https://docs.nextcloud.com/server/latest/admin_manual/installation/index.html).
After installation I navigate to *Settings* > *Overview* (of the Administration
section below) and look for security warnings. You can also use your URL in the
[official security scan](https://scan.nextcloud.com/) to check your instance.
## Security options
For further hardening I recommend changing the [User password policy](https://docs.nextcloud.com/server/latest/admin_manual/configuration_user/user_password_policy.html)
in the *Security settings* to enforce passwords with lower, uppercase, and
numeric characters. A best practice is to limit login attempts to 5 or less and
use [Two-factor authentication](https://docs.nextcloud.com/server/latest/admin_manual/configuration_user/two_factor-auth.html).
Another optimization is to [disable preview image generation](https://docs.nextcloud.com/server/latest/admin_manual/installation/harden_server.html#disable-preview-image-generation)
as mentioned in the official hardening and security guidance. This is achieved
by adding `enable_previews = 'false'` to the `config.php` file. The safest way
is to use the [occ command](https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/occ_command.html)